Wheel localizer, wheel localization device, system, method and computer program for locating a position of a wheel

ABSTRACT

Embodiments can provide a system, a wheel localizer, a wheel localization device, a method or a computer program for locating a position of wheel and/or for determining an acceleration of a wheel of a vehicle. The system for locating a position of at least one out of a plurality of wheels of a vehicle includes a detector configured to obtain information related to a tangential acceleration of the at least one wheel of the vehicle and an antilock braking system unit configured to obtain information related to angular rotations of the plurality of wheels. The system further includes a locator configured to determine the position of the at least one wheel based on the information related to the tangential acceleration of the at least one wheel and the information related to the angular rotations of the plurality of wheels.

FIELD

Embodiments of the present disclosure relate to a wheel localizer, awheel localization device, a method, a system and a computer program forlocating a position of a wheel and/or for determining an acceleration ofa wheel of a vehicle.

BACKGROUND

Tire Pressure Monitoring Systems (TPMS) are designed to monitor the airpressure inside of pneumatic tires on various types of vehicles.Therefore pressure sensors are used in the tires and the system mayreport the tire pressure information to the driver of the vehicle.Wireless transmission can be used to transmit information on thepressure data to a centralized receiver component in the vehicle. Such aconfiguration can enable the system to report or signal pressure lossesof the tires to the driver. Some known TPMS provide localizationinformation on the tire or wheel on top of pressure information so as toindicate to a driver of a vehicle the position of a wheel having apressure loss. Examples are indications on whether a pressure loss of atire of a wheel of a car is on the Front Left (FL) tire, the Front Right(FR) tire, the Rear Left (RL) tire, and/or the Rear Right (RR) tire.After replacement of a wheel or tire, assignment or re-assignment of thesensor signals to the positions on the vehicle may be necessary. Suchassignment can be carried out manually, for example, by using aLow-Frequency (LF) initializer, which is used to initialize eachindividual sensor upon indication from a system receiver. Theinitialization can be affected by sequentially activating anLF-initiator in the proximity of the respective sensor and receiving anaccording response with a unique identification from the sensor.

Some known TPMS systems utilize multiple LF-initializers, e.g. in termsof transmitter coils or inductors, for initialization of each individualsensor or wheel, for example, and they can be mounted in the wheelhousing of each wheel. The number of involved LF-initializers may rendersuch an approach uneconomic. Other concepts make use of differentreception levels of the LF-radio signals using transmitter coils atdifferent locations asymmetric to the wheels, e.g. one in the front andone in the back. These concepts are expensive and unsuitable forafter-market installation. Further concepts make use of the varyingreception power of the RF-signals transmitted by the sensors. Thereception power of such an RF-signal can be measured and the differentlocations can be distinguished by the different reception levels, e.g.evoked by different distances of the wheels. The larger the distancebetween a wheel and the corresponding receiver the lower the receptionpower. In some cars a distinction between the signals from the front andthe signals from the back is possible, as the receiver is located at anasymmetric position i.e. close to a rear axis, a distinction betweensignals from the left and right is rather difficult. This concept maysuffer from the complex propagation paths of the wireless signals, whichmay render an assignment of a reception level of a signal to a certainwheel difficult. Some concepts may use a set of acceleration sensors,which are installed in an orthogonal manner in each wheel to determinethe rotational direction of the wheels to distinguish left and rightwheels.

Another concept uses ABS (Anti-lock Braking System) signals to determinerotational frequencies of the wheels and relates or correlates them torotational frequencies determined based on TPMS signals, which may makeuse of radial acceleration sensors determining the acceleration changesas the sensor rotates with the wheel causing centrifugal acceleration ontop of gravitation.

SUMMARY

Embodiments are based on the finding that Original EquipmentManufacturers (OEMs) indicate a desire for a robust, cheap/costefficient and an energy efficient localization concept up to maximumspeed, such as up to 300 km/h. It is a further finding that existinglocalization concepts can have limitations regarding maximum speed,costs and energy efficiency. For example, when acceleration sensors areused to determine the rotational speed of a wheel, the occurringaccelerations depend on the rotational speed of the wheel. However, therelation can be of a quadratic nature, i.e. doubling the rotationalspeed of a wheel corresponds to four times the radial acceleration.Therefore, radial acceleration sensors may be limited at higher speeds.It is a further finding of embodiments that a tangential accelerationmay as well be exploited to determine a rotational speed of a wheel.Moreover, it is another finding that the tangential acceleration doesnot grow in a quadratic manner with the rotational speed of a wheel.Embodiments therefore exploit the tangential acceleration of a wheel inorder to determine a rotational speed or frequency of the wheel.

Embodiments may therewith provide the advantage that tangentialacceleration sensors, which are also referred to as X-sensors, may nothave a speed limitation such as at least some of the radial accelerationsensors. As the acceleration does not grow as vastly as for radialacceleration sensors, the tangential acceleration sensors may be used upto much higher rotational frequencies and therewith up to higher vehiclespeeds. Embodiments may therewith provide localization concepts whichare efficient and may have a high or even no speed limitation.

Embodiments are further based on a finding that a tangentialacceleration sensor may measure an accurate vehicle speed withoutabsolute acceleration information, which may be based on a calibrationprocess in manufacturing for a wide range speed. Moreover, a tangentialsensor may not have a direct current (DC) offset of sinusoidal signalsto detect an Angular Position of a Sensor (APS) and it may enable a costand energy efficient concept. Furthermore, tangential accelerationdetermination may provide the advantage that temperature compensationand a calibration may not be needed for an acceleration measurement,since relative measurements may be sufficient for determining arotational speed of a wheel.

Embodiments make use of information related to a tangential accelerationof at least one wheel of a vehicle. In the following a vehicle can beany vehicle using tires, as for example, a car, a van, a truck, a bus, aplane, a bike, a motorbike, etc. Although many embodiments will beexemplified using a car, any other vehicle can be utilized inembodiments. Embodiments provide a system for locating a position of atleast one out of a plurality of wheels of a vehicle. The systemcomprises a detector which is configured to obtain information relatedto a tangential acceleration of the at least one wheel of the vehicle.It is a finding of embodiments that the tangential acceleration of awheel of a vehicle provides an oscillating signal as the wheel rotatesin gravity. Moreover, the tangential acceleration is not assignificantly affected by different rotational speeds of the wheel as aradial acceleration, as will be detailed subsequently. In embodiments,the detector can be implemented as any means for detecting, a detectiondevice, a detection unit, a detection module, one or more sensors, etc.

The system further comprises an antilock braking system unit configuredto obtain information related to angular rotations of the plurality ofwheels. In embodiments the antilock braking system unit may beimplemented as any means for antilock braking, an antilock brake device,an antilock brake module, and it may comprise antilock braking systemsensors or detectors as will be detailed in the sequel. In other words,from an antilock braking system, angular rotations of the plurality ofwheels can be determined.

The system further comprises a locator configured to determine theposition of the at least one wheel based on the information related tothe tangential acceleration of the at least one wheel and theinformation related to the angular rotations of the plurality of wheels.The locator can be implemented as any locating means, such as a locatingdevice, a locating unit, a locating module, software which is executedon accordingly-adapted hardware, such as a processor, a digital signalprocessor (DSP), a multipurpose processor, a controller, etc. In otherwords, the locator may exploit knowledge on the angular rotations of theplurality of wheels on the vehicle as obtained from the antilock brakingsystem and it may compare these angular rotations to an angular rotationdetermined from the information related to the tangential accelerationof the at least one wheel. Therewith, the finding may be exploited thatfrom the tangential acceleration, information related to an angularfrequency or rotational speed of the wheel can be derived.

By matching the angular rotations determined from the tangentialaccelerations with the angular rotations from the antilock brakingsystem, signals with corresponding rotational frequencies can beassigned to each other. Since the positions of the wheels evoking theantilock braking system angular rotations are known, the locator candetermine the position of the at least one wheel based on the respectiveposition information from the antilock braking system. In other words,the locator can be configured to obtain the position of the at least onewheel further based on predetermined positions associated to theplurality of wheels and the information related to the angular rotationsof the plurality of wheels.

In further embodiments, the detector can comprise an acceleration sensorfor sensing information related to the tangential acceleration of the atleast one wheel of the vehicle. The acceleration sensor may correspondto an X-sensor mounted on the wheel. In embodiments such a tangentialacceleration sensor may be mounted on the tire or on the rim of thewheel. The acceleration sensor may correspond to a one-dimensionalsensor, for example, a sensor sensing the tangential acceleration or anyother acceleration, from which a tangential acceleration can bedetermined. In some embodiments, the acceleration sensor can correspondto a linear sensor; however, utilization of non-linear sensors inembodiments is also conceivable. Embodiments may not depend on the exacttangential accelerations, but on tangential acceleration changes, fromwhich information related to the angular rotations of the wheel isderivable.

In further embodiments, the locator can be configured to determine theposition of the at least one wheel by determining information related toa correlation of the information related to tangential acceleration ofthe at least one wheel and the information related to the angularrotations of the plurality of wheels of the vehicle. In other words, insome embodiments the locator may determine a correlation between angularrotations determined based on an antilock braking system and angularrotations determined based on the tangential acceleration of a wheel.Determining the correlation may correspond to determining any measure onhow the different angular rotations match each other. For example, oncean angular rotation is derived from the tangential acceleration of theat least one wheel, the wheel can be assigned to the position for whichthe antilock braking system unit indicates an angular rotation of therespective wheel closest to the angular rotation determined from thetangential acceleration.

In further embodiments, the antilock braking system unit may compriseone or more antilock braking system sensors to obtain the informationrelated to the angular rotations of the plurality of wheels. There areseveral possibilities for these antilock braking system sensors. Forexample, indicators may be mounted on the rim, which can be sensed fromthe chassis of the vehicle as the wheel rotates. Such indicators may beoptical indicators, magnetic indicators, electrical indicators, etc. Thesensors may then correspond to optical sensors, magnetic sensors,electrical sensors, etc. In some embodiments, one implementation may usea rotating plate or a disc, having correspondingly adapted gaps throughwhich an optical signal can be obtained. As the antilock braking systemhas this sensor assigned to a certain position, it is already known fromwhich position on the vehicle the angular rotation is measured by theantilock braking system.

In further embodiments, the detector can be configured to obtaininformation related to a tire pressure of the at least one wheel. Thelocator can be further configured to associate the information relatedto the tire pressure with the position of the at least one wheel. Inother words, once the position of the wheel has been determined, a tirepressure signal, as for example determined by a pressure sensor from aTire Pressure Monitoring System (TPMS), can also be assigned to thatposition. In some embodiments, information related to the tire pressureand information related to the tangential acceleration of the respectivewheel may be communicated using the same signal. Furthermore, the signalmay comprise an IDentification (ID), for example, in terms of a uniquenumber assigned to the respective TPMS-sensor. Therefore, the respectivetire pressure can be assigned to the location or position as determinedby the above method. That is to say in some embodiments the detector mayfurther comprise a tire pressure sensor. In some embodiments a tirepressure sensor and a tangential acceleration sensor may be integratedinto one device, wherein the device or combined sensor is also operableto provide according measurement results on the tangential accelerationand the tire pressure in one signal.

In further embodiments the detector and the locator can be configured tocommunicate in a wireless manner. In other words, radio signals may beused to communicate the respective information from the detector to thelocator. The detector can be configured to transmit information using aradio signal and the locator can be configured to receive informationfrom the radio signal. For example, some embodiments may uselow-frequency radio signals for transmitting the information. Inembodiments, any short range wireless communication standard or systemmay be used to communicate the information from the detector to thelocator. For example, any near field communication may be used, such asradio frequency identification (RFID), Zigbee, Bluetooth, etc. Hence, insome embodiments the detector may comprise typical transmittercomponents, such as a transmit antenna or loop, an amplifier, a filter,a mixer, an oscillator, etc. Correspondingly the locator may comprisetypical receiver components such as a receive antenna or loop, anamplifier, a filter, a mixer, an oscillator, etc.

In line with the above description, embodiments may provide a wheellocalizer for locating a position or a location of at least one out of aplurality of wheels of a vehicle. The wheel localizer comprises adetector configured to provide an acceleration signal, comprisinginformation related to a tangential acceleration of the at least onewheel of the vehicle. Moreover, the wheel localizer comprises anantilock braking system unit configured to provide a rotation signalcomprising information related to angular rotations of the plurality ofwheels. Furthermore, the wheel localizer comprises a locator configuredto receive the acceleration signal and the rotation and being furtherconfigured to provide a position signal comprising information relatedto the position of the at least one wheel based on the accelerationsignal and the rotation signal.

In other words, the wheel localizer may be implemented as one or morechips or integrated circuits. The detector may provide the accelerationsignal and the antilock braking system unit may provide the rotationsignal. The locator may then determine an expected rotation signal forthe at least one wheel from the acceleration signal and compare theexpected rotation signal with the rotation signal from the antilockbraking system unit.

In embodiments, the locator can be configured to provide the positionsignal further based on predetermined positions associated to theplurality of wheels and the information related to the angular rotationsof the plurality of wheels. In other words, as it was described above,the antilock braking system unit may have predetermined knowledge onwhich angular rotation relates to which one of the plurality of wheels.Using the predetermined knowledge on the position of the wheel with thecertain angular rotation, this angular rotation can be matched to theabove expected angular rotation and thus the position can be assigned.

In embodiments the detector may comprise an acceleration sensor forsensing information related to the tangential acceleration of the atleast one wheel of the vehicle. As it was explained above, theacceleration sensor may be mounted on the rim or the tire of the wheel.In embodiments, the acceleration sensor may correspond to aone-dimensional sensor and/or a linear sensor. The locator can beconfigured to determine the information related to the position of theat least one wheel by determining information related to a correlationof the information related to the tangential acceleration of the atleast one wheel and the information related to the angular rotations ofthe plurality of wheels of the vehicle. As described above, correlationsmay be determined between rotational signals from the antilock brakingsystem and the acceleration signal directly, or an expected rotationalsignal may be determined from the acceleration signal which can be usedfor the correlation. In line with the above description, the antilockbraking system unit may comprise one or more antilock braking systemsensors to obtain the rotation signal. The locator can be furtherconfigured to receive a pressure signal comprising information relatedto a tire pressure of the at least one wheel. The locator can be furtherconfigured to associate the information related to the tire pressurewith the position signal, i.e. with the position as determined from theangular rotation and the expected angular rotation. Furthermore, thedetector can be further configured to transmit information using a radiosignal and the locator can be further configured to receive theinformation from the radio signal in line with the above.

Embodiments further provide a wheel localization device for locating aposition of at least one out of a plurality of wheels of a vehicle. Thewheel localization device comprises one or more inputs for a firstsignal comprising information related to a tangential acceleration ofthe at least one wheel of the vehicle and for one or more second signalscomprising information related to angular rotations of the plurality ofwheels. The wheel localization device further comprises an output for anoutput signal comprising information related to the position of thewheel, wherein the output signal is based on the first signal comprisingthe information related to the tangential acceleration of the at leastone wheel of the vehicle and on the one or more second signalscomprising the information related to the angular rotations of theplurality of wheels.

In embodiments, the wheel localization device may be implemented as oneor more chips or integrated circuits. In some embodiments, the wheellocalization device may correspond to one of the above systems on onechip. For example, the wheel localization device may be implemented asan Application Specific Integrated Circuit (ASIC). In embodiments, theoutput signal may comprise information related to an association of thefirst signal to one of the angular rotations of the plurality of wheels.In other words, in some embodiments the wheel localization device mayprovide information to which one of the angular rotations from theplurality of wheels the respective tangential acceleration isassociated. The final localization, for example, the assignment of theposition of certain angular rotation to the tangential acceleration maybe carried out outside the wheel localization device.

Embodiments also provide a method for locating a position of at leastone out of a plurality of wheels of a vehicle. The method comprisesobtaining information related to a tangential acceleration of the atleast one wheel of the vehicle and obtaining information related toangular rotations of the plurality of wheels. The method furthercomprises determining the position of the at least one wheel based onthe information related to the tangential acceleration of the at leastone wheel and the information related to the angular rotations of theplurality of wheels in line with the above description.

In further embodiments, the method may further comprise determining theposition of the at least one wheel by determining information related toa correlation of the information related to the tangential accelerationof the at least one wheel and the information related to the angularrotations of the plurality of wheels of the vehicle. Hence, in line withthe above description, embodiments may carry out a correlation betweenthe tangential acceleration and the angular rotations. In furtherembodiments, the method may further comprise obtaining informationrelated to a tire pressure of the at least one wheel and associating theinformation related to the tire pressure with the position of the atleast one wheel. Moreover, in embodiments, the method may comprisetransmitting information using a radio signal and receiving theinformation from the radio signal as described above.

Embodiments further provide a computer program having a program code ona non-transitory medium for performing, when the computer program isexecuted on a computer or on a processor, a method for locating aposition of at least one out of a plurality of wheels of a vehicle, asdescribed above.

Embodiments can be further based on the finding that any sensor system,which is located in a wheel, may be battery powered. When having batterypowered devices, energy efficient operation may be desirable. It is afurther finding that some wheel sensoring systems use the radialacceleration in order to determine whether the system or wheel is inmotion or not. If low or no radial acceleration is determined, thesystem may be switched into a standby mode, i.e. into an energyefficient mode. It is a further finding of embodiments that a moreefficient utilization of such a system can be achieved if an actualacceleration is stored in a memory. With the stored value, the systemcan wake up and measure another acceleration. If the acceleration doesnot change or does not change more than a certain threshold, the systemmay go to the standby or energy efficient mode. If changes in theacceleration are detected, the system may be switched into measurementmode or run mode.

Embodiments provide a system for determining an acceleration of a wheelof a vehicle. The system comprises an acceleration sensor configured todetermine information related to an acceleration of the wheel. Inembodiments, the acceleration sensor can be implemented as any one- ormulti-dimensional sensor, which can be linear or non-linear. The systemfurther comprises a memory unit configured to store information relatedto the acceleration of the wheel. The memory can be any memory, such asa Random Access Memory (RAM), an Electronically Erasable ProgrammableRead-Only Memory (EEPROM), etc. The memory can, for example, be batterypowered as well; it may be versatile or non-versatile. The system mayfurther comprise a control unit which can be implemented as a controldevice, a control module, a controller, any means for controlling, aprocessor, a microprocessor, etc.

The control unit is configured to compare stored information related toa past acceleration of the wheel with recent information related to arecent acceleration of the wheel, where the control unit is configuredto operate the system in a standby mode when the stored informationdiffers from the recent information by less than a predeterminedthreshold. In other words, accelerations may be measured at differenttimes. A measurement at the first time is stored in the memory. At acertain time later, a second measurement is taken and compared to thefirst measurement. If the difference between the two measurements liesbelow the threshold, which can be set in a predetermined way, the systemis operated in standby mode. If acceleration changes are detected, thesystem can be switched into a measurement mode and provide more frequentmeasurements than in the standby mode. The time period between the firsttime and the second time, i.e. the wake-up settings for the abovecomparisons, may be preset as well. Hence, the wake-up intervals instandby mode can be adjusted and therewith the corresponding energyconsumption.

Embodiments may further provide an according method for determining anacceleration of a wheel of a vehicle. The method comprises determininginformation related to an acceleration of the wheel and storinginformation related to the acceleration of the wheel. The method furthercomprises comparing stored information related to a past acceleration ofthe vehicle with recent information related to a recent acceleration ofthe wheel. The method further comprises operating the system in astandby mode when the stored information differs from the recentinformation by less than a predetermined threshold.

Embodiments may further provide a computer program having a program codeon a non-transitory medium for performing, when a computer program isexecuted on a computer or on a processor, a method for determining anacceleration of a wheel of a vehicle according to the above description.

Embodiments may provide the advantage that higher speed limits forlocalization systems and sensors may be enabled using tangentialacceleration for localization concepts. Moreover, more cost-effectivesensors may be used, as tangential sensors may not need to be calibratedin order to determine the rotational speed of the wheel. Moreover, usingone of the above concepts, a sinusoidal signal may be used to detect anangular position of a sensor, which may have only a low or even no DCoffset. Furthermore, temperature compensation and calibration may not beneeded for acceleration measurements in embodiments. Embodiments mayonly make use of relative measurements.

BRIEF DESCRIPTION OF THE DRAWINGS

Some other features or aspects will be described using the followingnon-limiting embodiments of apparatuses and/or methods and/or computerprograms by way of example only, and with reference to the accompanyingFigures, in which

FIG. 1 shows an embodiment of a system for locating a position of awheel;

FIG. 2 shows an embodiment of a wheel localizer;

FIG. 3 shows an embodiment of a wheel localization device;

FIG. 4 illustrates a radial acceleration sensor;

FIG. 5 illustrates a radial acceleration sensor in a vehicle;

FIG. 6 illustrates a tangential acceleration sensor;

FIG. 7 illustrates a tangential acceleration sensor in a vehicle;

FIG. 8 depicts a view graph of an acceleration signal in an embodiment;

FIG. 9 illustrates different tangential accelerations in an embodiment;

FIG. 10 shows a view chart with tangential and radial accelerations;

FIG. 11 shows acceleration sensing in an embodiment;

FIG. 12 depicts an embodiment of the system for determining anacceleration of a wheel of a vehicle;

FIG. 13 shows a block diagram of a flowchart of a method for determiningan acceleration of a wheel of a vehicle;

FIG. 14 shows a flowchart of another embodiment of a method fordetermining an acceleration of a wheel; and

FIG. 15 illustrates a block diagram of a flowchart of an embodiment of amethod for locating a position of a wheel.

DETAILED DESCRIPTION

Various embodiments will now be described in more detail with referenceto the accompanying drawings. In the Figures, the thicknesses of lines,layers and/or regions may be exaggerated for clarity.

Accordingly, while embodiments are capable of various modifications andalternative forms, embodiments thereof are shown by way of example inthe Figures and will herein be described in detail. It should beunderstood, however, that there is no intent to limit embodiments to theparticular forms disclosed, but on the contrary, embodiments are tocover all modifications, equivalents, and alternatives falling withinthe scope of the invention.

Like numbers refer to like or similar elements throughout thedescription of the Figures. It will be understood that when an elementis referred to as being “connected” or “coupled” to another element, itcan be directly connected or coupled to the other element or interveningelements may be present. In contrast, when an element is referred to asbeing “directly connected” or “directly coupled” to another element,there are no intervening elements present. Other words used to describethe relationship between elements should be interpreted in a likefashion (e.g., “between” versus “directly between,” “adjacent” versus“directly adjacent,” etc.).

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises,” “comprising,” “includes” and/or “including,” when usedherein, specify the presence of stated features, integers, steps,operations, elements and/or components, but do not preclude the presenceor addition of one or more other features, integers, steps, operations,elements, components and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which embodiments belong. It will befurther understood that terms, e.g., those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

In the following description some components will be displayed inmultiple Figures carrying the same reference signs, but may not bedescribed multiple times in detail. A detailed description of acomponent may then apply to that component for all its occurrences.

FIG. 1 shows an embodiment of a system 10 for locating a position of atleast one out of a plurality of wheels of a vehicle. The system 10comprises a detector 12 configured to obtain information related to atangential acceleration of the at least one wheel of the vehicle. Thesystem 10 further comprises an antilock braking system unit 14configured to obtain information related to angular rotations of theplurality of wheels. The system 10 further comprises a locator 16configured to determine the position of the at least one wheel based onthe information related to the tangential acceleration of the at leastone wheel and the information related to the angular rotations of theplurality of wheels. FIG. 1 further shows the detector 12 is coupled tothe locator 16. Furthermore, the antilock braking system unit 14 iscoupled to the locator 16.

Optional features are indicated by dashed lines or boxes in thefollowing Figures. As FIG. 1 further indicates the locator 16 can beconfigured to obtain the position of the at least one wheel furtherbased on predetermined positions associated with the plurality of wheelsand the information related to the angular rotations of the plurality ofwheels. As further indicated in FIG. 1, the locator 16 can be configuredto determine the position of the at least one wheel by determininginformation related to a correlation of the information related to thetangential acceleration of the at least one wheel and the informationrelated to the angular rotations of the plurality of wheels of thevehicle.

As further shown in FIG. 1, the detector 12 may comprise an accelerationsensor 18 for sensing information related to the tangential accelerationof the at least one wheel of the vehicle. The acceleration sensor 18 maycorrespond to a one-dimensional and/or a linear sensor. Moreover, thedetector 12 may comprise a pressure sensor 24 such as a tire pressuresensor 24. The detector 12 can be further configured to obtaininformation related to a tire pressure of the at least one wheel andhence the locator 16 can be further configured to associate theinformation related to the tire pressure with the position of the atleast one wheel. FIG. 1 further shows the optional sensors 22 which canbe comprised in the antilock braking system unit 14. The antilockbraking system unit 14 may comprise one or more antilock braking systemsensors 22 to obtain the information related to the angular rotations ofthe plurality of wheels. Finally, FIG. 1 also shows that there may be aradio communication used between the locator 16 and the detector 12.More particularly, the detector may comprise typical transmittercomponents such as a transmit antenna or loop, a radio frequencyoscillator, a mixer, a power amplifier, etc. Correspondingly, thelocator 16 may comprise typical receiver components, such as one or morereceive antennas or loops, one or more filters, one or more oscillators,a low-noise amplifier, a converter, a mixer, etc.

FIG. 2 illustrates an embodiment of a wheel localizer 30 for locating aposition of at least one out of a plurality of wheels of a vehicle. Thewheel localizer 30 comprises a detector 12 which is coupled to a locator16. Moreover, the wheel localizer 30 comprises an antilock brakingsystem unit 14 which is also coupled to the locator 16. The detector 12is configured to provide an acceleration signal of the at least onewheel of the vehicle to the locator 16. The antilock braking system unit14 is configured to provide the rotation signal comprising informationrelated to angular rotations of the plurality of wheels to the locator16. The locator 16 is configured to receive the acceleration signal andthe rotation signal and to further provide a position signal comprisinginformation related to the position of the at least one wheel based onthe acceleration signal and the rotation signal.

The locator 16 can be further configured to provide the position signalfurther based on predetermined positions associated with the pluralityof wheels and the information related to the angular rotations of theplurality of wheels is indicated by the dashed line in FIG. 2. As alsoindicated in FIG. 2, the detector 12 may comprise an acceleration sensor18, which may correspond to a one-dimensional or a multi-dimensionalsensor, a linear or a non-linear sensor, respectively. The accelerationsensor 18 is configured to sense information related to the tangentialacceleration of the at least one wheel of the vehicle. As furtherindicated in FIG. 2, the locator 16 can be configured to determine theinformation related to the position of the at least one wheel bydetermining information related to a correlation 20 of the informationrelated to the tangential acceleration of the at least one wheel and theinformation related to the angular rotations of the plurality of wheelsof the vehicle. Furthermore, the antilock braking system unit 14 maycomprise one or more antilock braking system sensors 22 to obtain therotation signal. The locator 16 can be configured to receive a pressuresignal from the detector 12 comprising information related to a tirepressure of the at least one wheel where the locator 16 can be furtherconfigured to associate the information related to the tire pressurewith the position signal. Correspondingly, the detector 12 may furthercomprise a pressure sensor 24 for generating the pressure signal.Moreover, the detector 12 and the locator 16 can be accordinglyconfigured to exchange the respective information using radio signals asdescribed above.

FIG. 3 illustrates an embodiment of a wheel localization device 40 forlocating a position of at least one out of a plurality of wheels of avehicle. The wheel localization device 40 comprises one more inputs 42for a first signal comprising information related to a tangentialacceleration of the at least one wheel of the vehicle and for one ormore second signals comprising information related to angular rotationsof the plurality of wheels. Moreover, the wheel localization devicecomprises an output 44 for an output signal comprising informationrelated to the position of the wheel, wherein the output signal is basedon the first signal comprising the information related to the tangentialacceleration of the at least one wheel of the vehicle and on the one ormore second signals comprising the information related to the angularrotations of the plurality of wheels. In further embodiments the outputsignal may comprise information related to an association of the firstsignal to one of the angular rotations of the plurality of wheels. Inthe present embodiment the wheel localization device is implemented as asingle chip.

The above-described embodiments will now be detailed using the followingfurther Figures. In high-end Tire Pressure Monitoring Systems (TPMS), itmay be desirable for the vehicle to be aware of the locations ofrespective sensors, as, for example, front left, front right, rear left,rear right, to correctly indicate the location of the tire with lowpressure in a TPMS display unit. This process is also referred to astire localization in a TPMS application. A need of high-end TPMS systemscan be considered as increasing compared to conventional TPMS, whichhave no tire position information. Hence, there is a desire for majorTPMS suppliers and original equipment manufacturers to identify aninexpensive and reliable solution. One method, which can be used inembodiments, is a so-called hybrid tire location method. According tothe above description in the hybrid tire localization concept,information from the wheel rotations, such as angular speed or angularposition, measured by a sensor in the wheel, such as a Tire PressureSensor (TPS), is compared with information of wheel rotations or angularrotations measured by an ABS wheel speed sensor 22. Hence, measuring anangular position or angular speed of a TPS is part of the hybrid tirelocation concept. Conventional concepts may use a hybrid tire locationsolution with existing Z-axis, i.e. radial acceleration, sensors.

FIG. 4 illustrates such a Z-axis sensor 60, which is mounted on a wheel62, i.e., the rim or the tire, where the wheel 62 is shown in anidealized way in FIG. 4. The acceleration measured by this Z-axis sensorpoints away from the rotation axis of the wheel, i.e. radialaccelerations are measured. FIG. 5 illustrates the radial accelerationsensor 60 mounted on the rim of the wheel 62, where the wheel 62 isattached to a vehicle. As the wheel starts rotating or spinning, it canbe seen from FIG. 5 that a radial acceleration starts increasing.Moreover, the radial acceleration sensor is also affected bygravitation, which may take a more significant part of the overallradial acceleration when the rotation speed of the wheel 62 is ratherlow. FIGS. 4 and 5 illustrate the radial direction accelerationmeasurement of conventional TPMS applications. The acceleration measuredat the radial direction of the wheel 62, i.e. the Z-axis, is thesuperposition of mainly earth gravity and centrifugal force. Theacceleration induced by earth's gravity has a sinusoidal oscillation dueto wheel rotation. The acceleration induced by centrifugal force isproportional to the square of the angular speed of the wheel 62. Asinusoidal oscillation signal is mainly used to get the angularprecision of TPMS by measuring the phase of the tire rotation. Thecentrifugal force acceleration is used for motion detection.

As it has already been mentioned above, the centrifugal force is notconstant and as the wheel 62 starts rotating a time varying dynamic DCoffset in a sinusoidal oscillation depending on the driving conditionsis generated. Therefore, it is more complicated to calculate the phaseinformation of the sinusoidal oscillation. This means that a morecomplex algorithm may be needed for determining the rotational speed orthe angular rotation itself since the time varying dynamic DC offset hasto be compensated. Therefore, embodiments may provide the advantage thatless battery energy is consumed by using the tangential acceleration aswill be detailed subsequently. Another option would be to wait for astable vehicle speed, which takes more time and also consumes morebattery. Embodiments may therefore provide the advantage that anaccording measurement for determination of an angular rotation can bedetermined more quickly.

To detect the threshold speed for motion detection, the radial Z-sensormay measure the absolute acceleration value to calculate the vehiclespeed from a radial acceleration measurement. Measurements taken at lowspeeds may be disadvantageous because the radial acceleration valuealways includes both an acceleration of centrifugal force and anacceleration of gravity. A speed measurement from a radial Z-sensor maytherefore only be useful when the acceleration of the centrifugal forcebecomes dominant compared to the acceleration of gravity in total radialdirection acceleration.

Furthermore, a Z-sensor, i.e. a radial acceleration sensor may saturateat high speeds. For example, radial acceleration at 200 km/h could reachup to 500 g. The Z-sensor may also need to have a resolution below 1 gto measure the small sinusoidal oscillation in a radial acceleration forAPS. Therefore, radial acceleration sensors may have a speed limitation.On top of that, as pointed out above, the dynamic range of anAnalog/Digital Converter (ADC) may need to be very high. Moreover, ahigh DC offset on a small AC signal may be observed. The calibrationprocess of such a radial sensor may be rather expensive. Moreover, theremay be a low speed detection limit as well.

FIG. 6 illustrates an embodiment with an X-axis direction in the sensor,i.e. with a tangential acceleration sensor 18. FIG. 6 shows theacceleration sensor 18 mounted on the wheel 70, where the wheel is shownin an idealized way. As indicated by the arrow next to the tangentialacceleration sensor, accelerations in the tangential direction aremeasured by this sensor. FIG. 7 illustrates the wheel 70 with thetangential sensor 18 as mounted on a vehicle. In this embodiment, thetangential acceleration sensor 18 corresponds to a tangential directiong-sensor in the wheel 70. Embodiments may use such an X-sensor for APSmeasurements. Embodiments may therefore provide the advantage that thereis no or a high speed limitation as no or almost no radial accelerationon the X-sensor is measured. Ideally, the tangential acceleration maynot be affected at all by radial acceleration because of theorthogonality between these two accelerations. Embodiments using theX-sensor APS may be more energy efficient, since they may not have a DCoffset. The absence of the DC offset, or the enablement of a rathersimple cancellation algorithm for the DC offset, may enable a muchfaster APS algorithm and embodiments may enable to utilize less APSdrives due to the higher accuracy of phase angles. This may be due totangential sensors having a higher resolution as compared to radialsensors. Also embodiments may make use of a smaller Analog/DigitalConverter (ADC) range which may also enable a smaller Die or Chip sizeand may provide more cost efficient ASIC concepts. The wheel speed andnumbers of rotation and angular acceleration can be obtained bymeasuring the X-sensor frequency.

The speed of the vehicle v=2πf R,

where f=the frequency of wheel rotation and R=the radius of the tire.FIG. 8 illustrates a view chart showing the oscillation in gravitationalacceleration g as measured with the tangential acceleration sensor 18versus time. FIG. 8 also depicts a series of subsequent orientations ofthe wheel 70 with the acceleration sensor 18 measuring the accelerationas depicted at the bottom. Between the two bars in FIG. 8 there is oneperiod of oscillation, i.e. one revolution of the wheel. In the firstposition, the acceleration sensor 18 is on the top of the wheel causingzero tangential acceleration. In the second position, the accelerationsensor is on the left of the wheel 70 pointing towards the ground, i.e.measuring a positive g. After that the acceleration sensor 18 is rotatedto the bottom of the wheel and accordingly does not measure anytangential acceleration. In the first step, the acceleration sensor 18is on the right-hand side of the wheel pointing upwards and accordinglymeasuring a negative-g acceleration. At the fifth state the accelerationsensor 18 is again at the top of the wheel 70 and does not measure anyacceleration, similar to the above-described first state or position.

Embodiments may provide the advantage that an absolute value ofacceleration may not be needed because the frequency information asshown in FIG. 8 is not affected significantly by the error from theabsolute value of acceleration. The frequency information in thetangential acceleration signal represents the angular rotation of thewheel, as shown in FIG. 8. Therefore, a tangential sensor may not need acalibration process, rendering embodiments more efficient thanconventional concepts using a radial acceleration sensor. Embodimentsmay provide the advantage that the used tangential acceleration sensormay not have a speed limitation for a tire localization system and APS.Moreover, embodiments may allow for less battery consumption for APS dueto having a reduced DC offset or even no DC offset when using atangential acceleration sensor. Moreover, embodiments may save costs dueto smaller ADC ranges and reduced calibration efforts. Moreover,especially at low speeds, an accurate speed may still be detected withthe tangential acceleration sensor.

In the following a mathematical description will be provided for thedifferent accelerations. FIG. 9 shows a simplified representation of thewheel 70 with the tangential acceleration sensor 18. FIG. 9 shows acoordinate system at the top with x-(abscissa) and z-axis (ordinate).The origin of the coordinate system is located at the center of thewheel 70 together with the rotational axis of the wheel 70. In thediagram shown in FIG. 9 at the top, r represents the radius from thecenter to the sensor 18. R represents the tire radius. g expresses thegravity and θ corresponds to the CounterClockWise (CCW) direction anglefrom the x-axis. {acute over (ω)} represents dω/dt, i.e. the angularacceleration where ω corresponds to dθ/dt at the angular speed. X, Zrepresent the vehicle coordinates, while x, z represent the sensorcoordinates. Ax corresponds to the tangential direction (x-axisacceleration) and Az represents the radial direction (z-axisacceleration). The following equations show the theoretical approachshowing that a DC offset, which may be induced by centrifugal force, canbe removed by solving the equations of motion of tangential direction(X-sensor) and radial direction (Z-sensor). The equation of motion foran acceleration of tangential direction (Ax) and an acceleration ofradial direction (Az) can be written using the following equations:

Ax=−g cos θ−r{acute over (ω)}−R{acute over (ω)} sin θ  (1)

Az=−g sin θ+rω ² +R{acute over (ω)} cos θ  (2)

FIG. 10 shows another view graph which illustrates the acceleration gversus time, while it is assumed that the wheel 70 is accelerating, i.e.the rotational speed of the wheel is increasing. FIG. 10 shows twographs 80 and 82, wherein graph 80 represents the radial directiong-sensor Az, and 82 represents the tangential direction g-sensor Ax. Itcan be seen from FIG. 10 the X-sensor has almost no DC offset during theacceleration compared to the Z-sensor.

The above Equation (1) represents Ax and shows a missing term rw² whencompared with Az as given by Equation (2). The missing term constitutesthe time varying DC offset. Equation (1) also shows a very importantterm g cos θ, which is needed to calculate the APS. The term r{acuteover (ω)} is induced by tangential direction acceleration due to theangular acceleration and R{acute over (ω)} sin θ is induced by anacceleration of longitudinal motion from the wheel center. But these twoterms r{acute over (ω)} and R{acute over (ω)} sin θ are very smallcompared to g cos θ. Therefore these two terms can be neglected in someembodiments and the two terms may only be observed in significantcontribution when the wheel is accelerating or decelerating.

In the following a TPS with an X-axis single acceleration sensor 18 asshown in FIG. 6 will be assumed. In the present embodiment, an X-axissingle acceleration sensor 18 rather than a Z-axis sensor or two-axesX/Z-sensor is used. FIG. 11 depicts another coordinate system showingthe sensor 18 rotating around the origin of the coordinate system,similar to what was described with respect to FIG. 9. In the following,it will be explained how embodiments deal with the problem of energyconsumption. Energy consumption is important as for most of the timesthe vehicle is not in motion, i.e. measuring the acceleration wouldconsume energy which lowers the lifetime of the battery. Therefore,there is the desire to switch the sensor 18 into a standby mode when thevehicle is not in motion.

FIG. 12 shows an embodiment of a system 50 for determining anacceleration of a wheel 70 of a vehicle. The system 50 comprises anacceleration sensor 52 configured to determine information related to anacceleration of the wheel 70. The system 50 further comprises a memoryunit 54 configured to store information related to the acceleration ofthe wheel. The system 50 further comprises a control unit 56, which isconfigured to compare stored information related to a past accelerationof the wheel with recent information related to a recent acceleration ofthe wheel 70, wherein the control unit 54 is configured to operate thesystem 50 in standby mode when the stored information differs from therecent information by less than a predetermined threshold.

As FIG. 12 shows, the control unit 56 is coupled to the accelerationsensor 52 and a memory unit 54. The acceleration sensor 52 in thisembodiment may be a tangential acceleration sensor, a radialacceleration sensor, or any one- or multi-dimensional accelerationsensor. FIG. 13 shows a block diagram of a flowchart of an embodiment ofa method for determining an acceleration of a wheel 70 of a vehicle. Themethod comprises determining information related to an acceleration ofthe wheel 70 at 92 and storing information related to the accelerationof the wheel 70 at 94. Moreover, the method comprises comparing storedinformation related to a past acceleration of the wheel 70 with recentinformation related to a recent acceleration of the wheel 70 at 96. Themethod further comprises operating the system 50 in a standby mode whenthe stored information differs from the recent information by less thana predetermined threshold at 98. Embodiments may also provide a computerprogram for performing one of the above methods when executed on aprocessor or on an according hardware component. The computer programmay have a program code on a non-transitory media for performing, whenthe computer program is executed on a computer or on a processor, therespective method.

FIG. 14 illustrates another flowchart 100 of an embodiment of a methodfor determining an acceleration of a wheel 70. FIG. 14 shows 102, inwhich the TPS periodically wakes up to detect a vehicle motion bymeasuring an acceleration. Such wakeup can be carried out from a parkingstate of the vehicle. In conventional concepts a Z-sensor may be used tomeasure the radial direction acceleration. If TPS detects anacceleration of centrifugal force in parking mode, it may go into a runmode or a rolling state from parking state, figuring that a centrifugalacceleration means that the wheels are rotating and the vehicle ismoving. In some embodiments, according to the above description, asingle axis tangential sensor may be used as acceleration sensor, whichmay not be able to detect centrifugal acceleration but only theacceleration induced by earth's gravity depending on the angle positionof the TPS as shown in FIG. 11. Both embodiments may make use of anotherconcept for detecting the rolling of a wheel 70 from parking state tocover this motion detection.

As shown in FIG. 14, when a TPS goes into a stationary state or parkingstate, the TPS may store the later stationary g or acceleration value toa battery-powered memory unit 54 which can for example be implemented asa random access memory (RAM). In the following and in FIG. 14 this valueis referred to as Ax(i−1). In the stationary state, the TPS performs aperiodic wakeup to detect a motion at 102. When the TPS is woken up inthe stationary step, the TPS measures one sample, which is referred toas Ax(i) as shown at 104 in FIG. 14. Then, the control unit 56, in theTPS, may compare this recent acceleration value with the storedacceleration value Ax(i−1) as stored in the RAM 54 as shown at 106 inFIG. 14. If the magnitude of Ax(i)−Ax(i−1) is less than a threshold,where some tolerance is allowed due to, for example, temperature drifts,the vehicle is very likely to be still in a stationary state. The TPScan then return to power down mode, as shown in FIG. 14 at 108, where ameasurement has been carried out, just like for a radial accelerationsensor application. In some embodiments just a single measurement may becarried out. Prior to powering down at 108, the TPS may store the recentacceleration value for a future comparison as shown at 110. Hence, incase the vehicle is parked, only a small difference in energyconsumption may occur compared to a radial acceleration sensor.

If Ax(i) is different from Ax(i−1), then there is a high possibilitythat the vehicle is moving. In this case TPS can start to measure moreX-axis or tangential acceleration samples to estimate the speed bymeasuring the period or frequency of oscillation, as indicated at 112 inFIG. 14. Then, if the estimated speed exceeds the threshold, as shown at114 in FIG. 14, where the threshold can be defined by the TPMSapplication, the TPS goes into a rolling state as indicated at 116 inFIG. 14. As indicated at 118 in FIG. 14, whenever the speed falls belowthe threshold, the TPS may go back to power down. As shown in FIG. 14,acts 112 and 114 are optional. In other words, an embodiment once theacceleration threshold is exceeded in step 106, the APS may switch torun mode as shown at 116 directly, without considering the speedthreshold at 114. In embodiments in standby mode the system 50 or TPSmay wake up frequently. The period between such wakeups can be preset,e.g. it may correspond to 1, 2, 5, 10, 20, 30, 60, 120, 240, 480 s.

FIG. 15 shows a block diagram of a flowchart of an embodiment of amethod for locating a position of at least one out of a plurality ofwheels of a vehicle. The method comprises obtaining information relatedto a tangential acceleration of the at least one wheel of the vehicle at120 and obtaining information related to angular rotations of theplurality of wheels at 122. The method further comprises determining theposition of the at least one wheel 70 based on the information relatedto the tangential acceleration of the at least one wheel and theinformation related to the angular rotations of the plurality of wheelsat 124.

According to the above the method may further comprise obtaining theposition of the at least one wheel further based on predeterminedpositions associated to the plurality of wheels and the informationrelated to the angular rotations of the plurality of wheels. In furtherembodiments, the method can further comprise determining the position ofthe at least one wheel by determining information related to acorrelation of the information related to the tangential acceleration ofthe at least one wheel and the information related to the angularrotations of the plurality of wheels of the vehicle. In furtherembodiments, the method may comprise obtaining information related to atire pressure of the at least one wheel 70 and associating theinformation related to the tire pressure with the position of the atleast one wheel. The method may further comprise transmittinginformation using a radio signal and receiving information from theradio signal in line with the above description. As mentioned before,embodiments may provide computer programs having a program code on anone-transitional media for performing, when the computer program isexecuted on a computer, on a processor or on corresponding hardware, oneof the above-described methods.

A person of skill in the art would readily recognize that acts ofvarious above-described methods may be performed by programmedcomputers. Herein, some embodiments are also intended to cover programstorage devices, e.g., digital data storage media, which are machine orcomputer readable and encode machine-executable or computer-executableprograms of instructions, wherein the instructions perform some or allof the steps of the above-described methods. The program storage devicesmay be, e.g., digital memories, magnetic storage media such as magneticdisks and magnetic tapes, hard drives, or optically readable digitaldata storage media. The embodiments are also intended to cover computersprogrammed to perform said steps of the above-described methods or(field) programmable logic arrays ((F)PLAs) or (field) programmable gatearrays ((F)PGAs), programmed to perform said steps of theabove-described methods.

The description and drawings merely illustrate the principles of thedisclosure. It will thus be appreciated that those skilled in the artwill be able to devise various arrangements that, although notexplicitly described or shown herein, embody the principles of thedisclosure and are included within its spirit and scope. Furthermore,all examples recited herein are principally intended expressly to beonly for pedagogical purposes to aid the reader in understanding theprinciples of the invention and the concepts contributed by theinventor(s) to furthering the art, and are to be construed as beingwithout limitation to such specifically recited examples and conditions.Moreover, all statements herein reciting principles, aspects, andembodiments of the disclosure, as well as specific examples thereof, areintended to encompass equivalents thereof.

Functional blocks denoted as “means for . . . ” (performing a certainfunction) shall be understood as functional blocks comprising circuitrythat is adapted for performing or to perform a certain function,respectively. Hence, a “means for s.th.” may as well be understood as a“means being adapted or suited for s.th.”. A means being adapted forperforming a certain function does, hence, not imply that such meansnecessarily is performing said function (at a given time instant).

The functions of the various elements shown in the Figures, includingany functional blocks labeled as “means”, may be provided through theuse of dedicated hardware, such as “a processor”, “a determiner”, etc.as well as hardware capable of executing software in association withappropriate software. When provided by a processor, the functions may beprovided by a single dedicated processor, by a single shared processor,or by a plurality of individual processors, some of which may be shared.Moreover, explicit use of the term “processor” or “controller” shouldnot be construed to refer exclusively to hardware capable of executingsoftware, and may implicitly include, without limitation, digital signalprocessor (DSP) hardware, network processor, application specificintegrated circuit (ASIC), field programmable gate array (FPGA), readonly memory (ROM) for storing software, random access memory (RAM), andnon-volatile storage. Other hardware, conventional and/or custom, mayalso be included. Similarly, any switches shown in the Figures areconceptual only. Their function may be carried out through the operationof program logic, through dedicated logic, through the interaction ofprogram control and dedicated logic, or even manually, the particulartechnique being selectable by the implementer as more specificallyunderstood from the context.

It should be appreciated by those skilled in the art that any blockdiagrams herein represent conceptual views of illustrative circuitryembodying the principles of the disclosure. Similarly, it will beappreciated that any flow charts, flow diagrams, state transitiondiagrams, pseudo code, and the like represent various processes whichmay be substantially represented in computer readable medium and soexecuted by a computer or processor, whether or not such computer orprocessor is explicitly shown.

Furthermore, the following claims are hereby incorporated into theDetailed Description, where each claim may stand on its own as aseparate embodiment. While each claim may stand on its own as a separateembodiment, it is to be noted that—although a dependent claim may referin the claims to a specific combination with one or more otherclaims—other embodiments may also include a combination of the dependentclaim with the subject matter of each other dependent claim. Suchcombinations are proposed herein unless it is stated that a specificcombination is not intended. Furthermore, it is intended to include alsofeatures of a claim to any other independent claim even if this claim isnot directly made dependent to the independent claim.

It is further to be noted that methods disclosed in the specification orin the claims may be implemented by a device having means for performingeach of the respective steps of these methods.

Further, it is to be understood that the disclosure of multiple steps orfunctions disclosed in the specification or claims may not be construedas to be within the specific order. Therefore, the disclosure ofmultiple steps or functions will not limit these to a particular orderunless such steps or functions are not interchangeable for technicalreasons.

Furthermore, in some embodiments a single step may include or may bebroken into multiple substeps. Such substeps may be included and part ofthe disclosure of this single step unless explicitly excluded.

What is claimed is:
 1. A system for locating a position of at least oneout of a plurality of wheels of a vehicle, comprising: a detectorconfigured to obtain information related to a tangential acceleration ofthe at least one wheel of the vehicle; an antilock braking system unitconfigured to obtain information related to angular rotations of theplurality of wheels; and a locator configured to determine the positionof the at least one wheel based on the information related to thetangential acceleration of the at least one wheel and the informationrelated to the angular rotations of the plurality of wheels.
 2. Thesystem of claim 1, wherein the locator is configured to obtain theposition of the at least one wheel further based on predeterminedpositions associated with the plurality of wheels and the informationrelated to the angular rotations of the plurality of wheels.
 3. Thesystem of claim 1, wherein the detector comprises an acceleration sensorfor sensing information related to the tangential acceleration of the atleast one wheel of the vehicle.
 4. The system of claim 3, wherein theacceleration sensor comprises a one dimensional sensor or a linearsensor, or both.
 5. The system of claim 1, wherein the locator isconfigured to determine the position of the at least one wheel bydetermining information related to a correlation of the informationrelated to the tangential acceleration of the at least one wheel and theinformation related to the angular rotations of the plurality of wheelsof the vehicle.
 6. The system of claim 1, wherein the antilock brakingsystem unit comprises one or more antilock braking system sensorsconfigured to obtain the information related to the angular rotations ofthe plurality of wheels.
 7. The system of claim 1, wherein the detectoris further configured to obtain information related to a tire pressureof the at least one wheel and wherein the locator is further configuredto associate the information related to the tire pressure with theposition of the at least one wheel.
 8. The system of claim 7, whereinthe detector further comprises a tire pressure sensor.
 9. The system ofclaim 1, wherein the detector is further configured to transmitinformation using a radio signal and wherein the locator is furtherconfigured to receive information from the radio signal.
 10. A wheellocalizer for locating a position of at least one out of a plurality ofwheels of a vehicle, comprising a detector configured to provide anacceleration signal comprising information related to a tangentialacceleration of the at least one wheel of the vehicle; an antilockbraking system unit configured to provide a rotation signal comprisinginformation related to angular rotations of the plurality of wheels; anda locator configured to receive the acceleration signal and the rotationsignal and being further configured to provide a position signalcomprising information related to the position of the at least one wheelbased on the acceleration signal and the rotation signal.
 11. The wheellocalizer of claim 10, wherein the locator is configured to provide theposition signal further based on predetermined positions associated withthe plurality of wheels and the information related to the angularrotations of the plurality of wheels.
 12. The wheel localizer of claim10, wherein the detector comprises an acceleration sensor configured tosense information related to the tangential acceleration of the at leastone wheel of the vehicle.
 13. The wheel localizer of claim 12, whereinthe acceleration sensor comprises a one dimensional sensor or a linearsensor, or both.
 14. The wheel localizer of claim 10, wherein thelocator is configured to determine the information related to theposition of the at least one wheel by determining information related toa correlation of the information related to the tangential accelerationof the at least one wheel and the information related to the angularrotations of the plurality of wheels of the vehicle.
 15. The wheellocalizer of claim 10, wherein the antilock braking system unitcomprises one or more antilock braking system sensors configured toobtain the rotation signal.
 16. The wheel localizer of claim 10, whereinthe locator is further configured to receive a pressure signalcomprising information related to a tire pressure of the at least onewheel, and wherein the locator is further configured to associate theinformation related to the tire pressure with the position signal. 17.The wheel localizer of claim 16, wherein the detector further comprisesa tire pressure sensor for generating the pressure signal.
 18. The wheellocalizer of claim 10, wherein the detector is further configured totransmit information using a radio signal and wherein the locator isfurther configured to receive the information from the radio signal. 19.A wheel localization device for locating a position of at least one outof a plurality of wheels of a vehicle, comprising one or more inputsconfigured to receive a first signal comprising information related to atangential acceleration of the at least one wheel of the vehicle andconfigured to receive one or more second signals comprising informationrelated to angular rotations of the plurality of wheels; and an outputconfigured to provide an output signal comprising information related tothe position of the wheel, wherein the output signal is based on thefirst signal comprising the information related to the tangentialacceleration of the at least one wheel of the vehicle and on the one ormore second signals comprising the information related to the angularrotations of the plurality of wheels.
 20. The wheel localization deviceof claim 19, wherein the output signal comprises information related toan association of the first signal to one of the angular rotations ofthe plurality of wheels.
 21. A system for determining an acceleration ofa wheel of a vehicle, comprising an acceleration sensor configured todetermine information related to an acceleration of the wheel; a memoryunit configured to store information related to the acceleration of thewheel; and a control unit configured to compare stored informationrelated to a past acceleration of the wheel with recent informationrelated to a recent acceleration of the wheel received from theacceleration sensor, wherein the control unit is configured to operatethe system in a standby mode when the stored information differs fromthe recent information by less than a predetermined threshold.
 22. Amethod for locating a position of at least one out of a plurality ofwheels of a vehicle, comprising: obtaining information related to atangential acceleration of the at least one wheel of the vehicle;obtaining information related to angular rotations of the plurality ofwheels; and determining the position of the at least one wheel based onthe information related to the tangential acceleration of the at leastone wheel and the information related to the angular rotations of theplurality of wheels.
 23. The method of claim 22, further comprisingobtaining the position of the at least one wheel further based onpredetermined positions associated with the plurality of wheels and theinformation related to the angular rotations of the plurality of wheels.24. The method of claim 22, further comprising determining the positionof the at least one wheel by determining information related to acorrelation of the information related to the tangential acceleration ofthe at least one wheel and the information related to the angularrotations of the plurality of wheels of the vehicle.
 25. The method ofclaim 22, further comprising obtaining information related to a tirepressure of the at least one wheel and associating the informationrelated to the tire pressure with the position of the at least onewheel.
 26. The method of claim 22, further comprising transmittinginformation using a radio signal and receiving the information from theradio signal.
 27. A computer program having a program code on anon-transitory media for performing, when the computer program isexecuted on a computer or on a processor, a method for locating aposition of at least one out of a plurality of wheels of a vehicle,comprising: obtaining information related to a tangential accelerationof the at least one wheel of the vehicle; obtaining information relatedto angular rotations of the plurality of wheels; and determining theposition of the at least one wheel based on the information related tothe tangential acceleration of the at least one wheel and theinformation related to the angular rotations of the plurality of wheels.